From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mslow3.mail.gandi.net (mslow3.mail.gandi.net [217.70.178.249]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8F15A32D7F0 for ; Wed, 17 Dec 2025 14:21:52 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.70.178.249 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765981315; cv=none; b=qLH6Vxz7UOm+B66lH86G4ldhiOfrtScCsonG/KJMP259ilLBZ7bJOXDFIb1BaZjHi7basCJ3iJwbrTHSLZcJxJsH/KhV4wZlZ+ZOXr5E9MAQpwD+n/tG6ldLpC6BlDA/iIXdhieXrVUSWG+vxU6O3wWXm02UGb/L/cdfl/n8Tqo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1765981315; c=relaxed/simple; bh=iL1MWYxWeBrBNEUb98kU9cxFu6B2GwRY+Jgi6gDKsm4=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=jrU1NRG4RQ6vjWBW7UQra1hwGo7GPneOSL1O7J56wOJD871BoMN6JNIuYUh6R/7Du2J10VFtooscONTYVoe4DCiZpVGnvTIDfuBHMgga9CQO6D0zbIfRUCjg6o3fdw73X5VuVrvD6xEjMo3/ijH2TFl6Y4rODaja1ui8c3u6LHo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org; spf=pass smtp.mailfrom=xenomai.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b=TTFR8lcG; arc=none smtp.client-ip=217.70.178.249 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=xenomai.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=xenomai.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=xenomai.org header.i=@xenomai.org header.b="TTFR8lcG" Received: from relay2-d.mail.gandi.net (relay2-d.mail.gandi.net [217.70.183.194]) by mslow3.mail.gandi.net (Postfix) with ESMTP id 79AEA580EF7 for ; Wed, 17 Dec 2025 14:21:49 +0000 (UTC) Received: by mail.gandi.net (Postfix) with ESMTPSA id 83166430BB; Wed, 17 Dec 2025 14:21:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=xenomai.org; s=gm1; t=1765981301; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=LWwvxZ7xsRL8X4O3qKuotroyjdvtgF7R8J94qlxIhrQ=; b=TTFR8lcGCHnsVbKQfDiTI6gOLaf5etk7wSLA24bDIRd/4nrkhL+9twwp5KL4nX93vdu+xo GIxC11gO/v/L9m/ud5oG7FrC5hQuFbrLkCg+sr/HNGwLq4WgX8EmEhyEP416ZbyYS7WQYj p5E71H6ObG4BBbQPLjwy+ZDaLEhv/75z+ioFWkN0OVm4EXpoTXN9XIShS+uiDuLCehnsCm FSgPWd9DhHwocV+kuVRWXkbTJjxTggwAYR/TAYZILOW4Nb2uUso0h5Kn3mjX+En+lM2/AB 6Z+ua2o/dI6m7Z+vVkkitQtsGavyTuX7t3QTvKgXH6HPqUiGPtwqpCv5aXWblA== From: Philippe Gerum To: Jan Kiszka Cc: Florian Bezdeka , Philippe Gerum , xenomai@lists.linux.dev Subject: Re: [PATCH RFC Dovetail 6.1 0/3] arm64: Enable in-kernel FPU / FPSIMD usage In-Reply-To: (Jan Kiszka's message of "Wed, 17 Dec 2025 13:46:38 +0100") References: <20251119-flo-6-1-arm64-fpsimd-test-enablement-v1-0-8653c0b573fd@siemens.com> <875xaq88tf.fsf@xenomai.org> <0b02043cfe5b2032611180d514dcb2eff690d844.camel@siemens.com> <87h5txuqhp.fsf@xenomai.org> User-Agent: mu4e 1.12.12; emacs 30.2 Date: Wed, 17 Dec 2025 15:21:36 +0100 Message-ID: <87sed9p4sv.fsf@xenomai.org> Precedence: bulk X-Mailing-List: xenomai@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain X-GND-Sasl: rpm@xenomai.org X-GND-Score: -100 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeefgedrtddtgdegvdejlecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnecujfgurhephffvvefujghffgffkfggtgesthdtredttdertdenucfhrhhomheprfhhihhlihhpphgvucfivghruhhmuceorhhpmhesgigvnhhomhgrihdrohhrgheqnecuggftrfgrthhtvghrnhepvdelhfdvheekudehveelgeeitdeujefgkefhieejfedvieejkeegiefgjefhkeegnecukfhppedvrgdtudemvgdtrgemudelsgemfegtugdtmeelkeelrgemhegtgegsmegsjehffhemsggrfhenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepihhnvghtpedvrgdtudemvgdtrgemudelsgemfegtugdtmeelkeelrgemhegtgegsmegsjehffhemsggrfhdphhgvlhhopehphihrohdpmhgrihhlfhhrohhmpehrphhmseigvghnohhmrghirdhorhhgpdhqihgupeekfeduieeigeeftdeuuedpmhhouggvpehsmhhtphhouhhtpdhnsggprhgtphhtthhopeegpdhrtghpthhtohepgigvnhhomhgriheslhhishhtshdrlhhinhhugidruggvvhdprhgtphhtthhopehphhhilhhiphhpvghgvghruhhmsehgmhgrihhlrdgtohhmpdhrtghpthhtohepfhhlohhrihgrnhdrsggviiguvghkrgesshhivghmvghnshdrtghomhdprhgtphhtt hhopehjrghnrdhkihhsiihkrgesshhivghmvghnshdrtghomh X-GND-State: clean Jan Kiszka writes: > On 15.12.25 12:19, Florian Bezdeka wrote: >> On Thu, 2025-12-11 at 13:56 +0100, Philippe Gerum wrote: >>> Florian Bezdeka writes: >>> >>>> On Mon, 2025-12-01 at 17:29 +0100, Philippe Gerum wrote: >>>>> Florian Bezdeka writes: >>>>> >>>>>> Hi all, >>>>>> >>>>>> these are the necessary backports for dovetail 6.1 that would allow us to >>>>>> enable the in-kernel FPU usage of switchtest. This is currently not >>>>>> possible as dovetail < 6.12 does not allow / implement the necessary fpsimd >>>>>> context switching. >>>>>> >>>>>> I have backported the necessary patches down to 5.10. That would allow >>>>>> us to unconditionally enable the tests for the xenomai3-next branch. I >>>>>> will send out the 5.15 and 5.10 series once we agreed that this version >>>>>> (targeting 6.1) is correct. >>>>>> >>>>>> Please note that there is a small problem with this series. Patch 1 >>>>>> removes the check/flag that was used by the dovetail enablement code to >>>>>> detect in-band FPU usage. The new flag is implemented differently in >>>>>> patch 2. Patch 2 also fixes the usage of that flag. I had no better >>>>>> idea. Otherwise I would have to delete? the in-kernel fpu preemption >>>>>> code (temporary). >>>>> >>>>> TIF_KERNEL_FPSTATE is not covering a preemption of a softirq handler >>>>> using the NEON unit by an oob thread when PREEMPT_RT is disabled, kernel >>>>> or user for that matter. i.e. It looks like this aspect was overlooked >>>>> during the busy -> TIF_KERNEL_FPSTATE transition for Dovetail, so a >>>>> broader fix may be required. We may have to use a marker which covers >>>>> any type of preempted context. >>>>> >>>> >>>> I agree, but this is something that we should address in addition / on >>>> top, no? >>>> >>> >>> Yep, would make backporting easier. >>> >>>> This issue seems to affect all versions of dovetail. If we do the >>>> backports first we can address the issue on the same feature set. That >>>> should simplify the back-porting again. Did I miss something? >>>> >>> >>> Agreed. >> >> How do we proceed now? Once applied to 6.1 I can send out the versions >> for 5.15 and 5.10 so Jan can apply them as well. >> > > Philippe, do you plan to update 6.1 soon? Or should I already take over > 6.1, given that 6.18 is on the horizon and you would likely stop 6.1 for > evl and dovetail soon? > Please take over. -- Philippe.